The present invention relates to the formation of a cosmetic and chemically stable aqueous hydrogen peroxide-containing dental gel having an acid pH of about 4.5-6, comprising a compatible system of specified amounts of specific dental components.
Until now, it has been difficult to formulate a cosmetic and chemically stable hydrogen peroxide gel with appropriate thickening/gelling agents, humectants, surfactants and flavor for oral application. However, after extensive experimentation on various mixtures of components in the hydrogen-peroxide dental gel product, a compatible system of water, polyoxyethylene-polyoxypropylene block copolymer gelling agent, polyethylene glycol humectant, nonionic surfactant, sweetening agent and flavor has been discovered. This dental product is in the form of a stable rigid gel having improved chemical and cosmetic stability and improved taste.
It has long been recognized in the art that hydrogen peroxide and other peroxygen-containing agents are effective in curative and/or prophylactic treatments with respect to cleaning caries dental plaque, gingivitis, periodontitis, mouth odor, tooth stains, recurrent aphthous ulcers, denture irritations, orthodontic appliance lesions, postextraction and postperiodontal surgery, traumatic oral lesions and mucosal infections, herpetic stomatitis and the like. Peroxide-containing agents in the oral cavity exert a chemomechanical action generating thousands of tiny oxygen bubbles produced by interaction with tissue and salivary enzymes. Peroxide mouthrinses and other oral preparations prevent colonization and multiplication of anaerobic bacteria known to be associated with periodontal disease. Peroxygen-containing gels or pastes are indicated and/or desirable where it is required to selectively treat areas for more than a few seconds, such gels and pastes tending to remain at the site of application for a time sufficient for the peroxide to manifest its maximum effectiveness.
It is also known that most peroxy compounds such as hydrogen peroxide in oral compositions tend to be unstable in storage due to incompatibility with, or interaction with, other common ingredients in the composition, and lose the capacity to release active or nascent oxygen over relatively short periods of time. This adversely affects both the chemical stability of the composition as well as the cosmetic stability of the final product, particularly in the gel product containing hydrogen peroxide.
The prior art has attempted to solve said problems by using a variety of stabilizers for dental compositions in assorted forms such as tablets, chewing gum, mouthwashes, toothpastes or powder containing a hydrogen peroxide, as shown in U.S. Pat. No. 4,226,851 wherein is disclosed an aqueous mouthwash containing hydrogen peroxide, flavor, zinc chloride and water soluble Vitamin E which stabilizes the hydrogen peroxide in the mouthwash. U.S. Pat. No. 4,302,441 discloses solid oral products (tablets and chewing gum) containing urea hydrogen peroxide in gum bases such as jelutong, rubber latex, vinylite resins, etc., and in methyl, ethyl and sodium carboxymethyl cellulose carriers, free of glycerol, also containing sweeteners such as sodium saccharinate, xylitol, sorbitol, and mannitol and flavors. U.S. Pat. No. 4,476,108 discloses an admixture of a peroxidase, a peroxide and a donor molecule such as phenylethylamine, tyrosine, tryptophan, benzoic acid, salicylic acid, hydroquinone, dihydrophenyl-alanine, vanillan and paraaminobenzoic acid, in a carrier such as water (mouthwash) or in the form of a paste, gel or powder. U.S. Pat. No. 4,431,631 discloses an aqueous oral solution containing hydrogen peroxide, glycerine and/or sorbitol humectant, 0.5-3% pluronic-type surfactant, polyoxyethylenated sorbitol monofatty acid ester surfactant, sweetener and flavor.
The prior art also discloses dental compositions containing a hydrogen peroxide and an additional component to effect stabilization, such as ascorbic acid in U.S. Pat. No. 3,886,265, wherein is disclosed tablets, lozenges, chewing gum or an aerosol or spray form containing a peroxide such as hydrogen peroxide and an ene-diol compound such as ascorbic acid, effective against bad breath.
U.S. Pat. No. 4,521,403 discloses a method of controlling and treating periodontal diseases by washing the teeth with an aqueous or aqueous alcoholic solution of a hydrogen peroxide and a povidone-iodine complex (complex of iodine with 1-vinyl-2-pyrrolidone polymers). These two ingredients are mixed only prior to use U.S. Pat. No. 4,592,487 discloses an antiplaque dentifrice in the form of a toothpaste or gel containing the two components, a peroxide and povidone-iodone complex, each separately mixed with conventional dentifrice components, and kept separated until admixed and dispensed from a special dual compartment container/mixer/dispenser device.
U.S. Pat. No. 4,592,488 discloses an oral composition containing an iodophor or quaternary ammonium compound and a peroxy compound such as hydrogen peroxide in the form of an aqueous or aqueous alcoholic solution prior to combining the two components into an oral mouthwash.
U.S. Pat. No. 4,592,489 discloses a two-part container for dispensing an oral mouthwash containing the povidone-iodine complex solution separate from the hydrogen peroxide solution and mixing prior to dispensing.
Dental compositions containing other oxidizing agents in lieu of the hydrogen peroxide are also disclosed in the prior art.
U.S. Pat. No. 4,522,805 and 4,567,036 disclose a stable toothpaste to aid in controlling periodontal disease, containing an oxidizing agent such as carbamide peroxide (urea peroxide) which dissociates into urea and hydrogen peroxide in the oral cavity, in a paste carrier comprising an anionic detergent, sorbitol and glycerin humectant and a thickening agent such as gum tragacanth, sodium alginate or sodium carboxymethyl cellulose.
U.S. Pat. No. 4,405,599 discloses toothpaste containing calcium peroxide and sodium perborate oxidizing agents; dicalcium phosphate, calcium carbonate and magnesium carbonate cleaning agents; sorbitol humectant; cornstarch and cellulose gum thickening agents, and an anionic detergent.
U.S. Pat. No. 4,223,003 discloses a toothpaste or toothpowder containing peroxide-containing substances such as magnesium peroxide and conventional dentifrice components.
U.S. Pat. No. 4,537,765 discloses a toothpaste having a pH of 9.2-10.5 containing a peroxydiphosphate salt, a polyethylene glycol humectant, a thickener such as colloidal silica, carboxyvinyl polymer, cellulose gums, or hectorite; a polishing agent such as silica or hydrated alumina and anionic or nonionic surfactants such as Pluronic F108.
However, none of the aforesaid patents disclose the preparation of hydrogen peroxide dental gels containing the essential specific components of a polyethylene glycol humectant, a non-ionic surfactant, flavor, and a polyoxyethylene polyoxypropylene block copolymer thickening agent in the formation of a stable dental gel.
The prior art also discloses processes of preparing other peroxide gels as shown in U.S. Pat. No. 3,657,413 and the article by Assay et al, "Stability of Hydrogen Peroxide in Certain Pharmaceutical Gels" Cosmetics and Toiletries, 54-56, 91, September 1976. The patent discloses a clear gel comprising urea peroxide, glycerol, a carboxypolymethylene polymer and flavor; prepared by dispersing the polymer into the glycerol with high speed stirring at reduced pressure and then dissolving the urea peroxide and other ingredients in the thickened polymer/glycerol solution yielding a viscous gel. The article discloses methyl cellulose gels for treating surface cuts, bleaching hair and for deodorant purposes containing 0.1% oxine as stabilizer for the hydrogen peroxide; prepared by dispersing the methyl cellulose in water using an electric stirrer and then neutralizing with tri-ethanolamine to yield a gel; or dispersing in hot water until well hydrated, refrigerating until solidified and stirring until a gel is obtained, adding the stabilizer oxine to the gel, followed by the addition of the hydrogen peroxide. Other stabilizers which are not as effective as oxine include hexamine, benzoic acid or urea.
Hydrogen peroxide gels containing polyoxyethylene polyoxypropylene block copolymers as the gelling/thickening agent is disclosed in U.S. Pat. Nos. 3,639,574 and 4,537,778. The former patent discloses a stable hydrogen peroxide gel for use in hair bleaching and treating surface cuts, using polyoxyethylene polyoxypropylene block copolymers as gelling agents in amounts of 22-79% of the total compositions.
This is not a dental gel, does not contain the polyethylene glycol humectant, sodium saccharine sweetener, or flavor which are essential ingredients in the dental gel. The latter patent discloses an aqueous oral preparation which may be in the form of a mouthrinse, a paste or a gel containing hydrogen peroxide, a flavor and 20% of a thickener (for the gel form), 1-20% polyhydric alcohols such as glycerol and sorbitol, 0.1-10% nonionic surfactants such as Tweens (polysorbate) and/or Pluronics. The Pluronic (F127) is the preferred gelling agent (5-50%). There is no mention of polyethylene glycol humectant which is the exclusive effective humectant used in this formulation.
Moreover, the prior art does not disclose a cosmetic and chemically stable aqueous hydrogen peroxide dental gel having a pH of 4.5-6.0 containing as the essential ingredients, a polyoxyethylene polyoxypropylene block copolymer gelling agent, a polyethylene glycol humectant, a nonionic surfactant, sweetener, i.e. sodium saccharin and flavor, in specified proportions.